The present invention relates to hydraulic jacks for lifting loads such as automobiles and other heavy objects. More specifically, it relates to a device and method for conveniently and rapidly applying input energy needed to raise the ram piston of a hydraulic jack.
Hydraulic pistons are well known in the art, employing the well known principle of hydraulic leverage to impart an enormous force to a lifting ram under mechanical advantage. A small force is repeatedly applied to a plunger in a hydraulic cylinder which connects to a larger cylinder through an orifice. The numerous small repeated force applications to the plunger in the small cylinder are converted to a large force exerted by a ram piston in the large cylinder through known structures.
Typically, the force applied to the plunger in the small cylinder is manually applied through a pivoting handle, which is often removable. The handle acts as a lever having, to some degree, its own mechanical advantage. Thus, while the user applies a hand load to the end of the handle remote from the pivot point, the handle applies a load to the plunger at a moving point on its length nearer the pivot point, thereby multiplying the hand load to a load on the plunger in a range, typically, of about 10-15 times the hand load.
In another configuration known in the art, a motor may be connected to a hydraulic jack system. The motor may be configured to apply a reciprocating load to the plunger through a gear box which then applies a rotational force to an eccentric cam. The cam transmits a reciprocating force to the plunger.
However, problems remain in the prior art. Where a handle is used to apply a repeating load to the plunger, the handle presents a dangerous obstacle if it is left connected to the jack after the jack is used to elevate a load. Persons walking by the jack may accidentally knock the protruding handle and move the jack, thereby endangering the security of an elevated load. Storing a jack activated by a removable handle will always require storing the handle along with the jack. In a busy workshop, a handle may easily become separated from the jack, thus creating problems and inconvenience when next the jack is to be used. Where an electrical motor is mounted on a jack system for providing a reciprocating force to the plunger, inconvenience may be caused by electrical conduits extending from the motor. Moreover, the motor itself, when mounted to the jack system, creates an additional protrusion which adds to the profile of the jack, thus providing an additional source of danger by presenting added structure that may be accidentally knocked into when the jack system is supporting an elevated load.
Thus, there remains in the art a need for a low profile hydraulic jacking system that may be conveniently and rapidly activated by a user. The present invention satisfies these and other needs.